Module 7 Introduction to Anemia Acknowledgments Ministry of Health Guyana Centers for Disease Control and Prevention CDC Global AIDS Program GAP Guyana Centers for Disease Control and Prevention CDC Atlanta American Society for Clinical Pathology ASCP Objectives Upon completion of this lesson the student will be able to Discuss manual reticulocyte counts including Principle of supravital stains Procedure acceptable specimens and sources of error Calculation of relative and absolute reticulocyte counts Normal reference values expressed in both relative and absolute numbers Discuss the significance of increased or decreased reticulocytes in the blood Review erythropoiesis and RBC survival including regulatory factors involved and substances needed for normal red cell and haemoglobin production Objectives Define the term anemia including both laboratory and functional definitions Contrast true and pseudo anemia based on RBC mass and plasma volume Discuss the haematologic response to anemia including signs of accelerated erythropoiesis Discuss the physiologic response to anemia including clinical symptoms and physical findings Objectives Contrast the morphologic and etiologic pathophysiologic classifications of anemia Discuss the following tests that can aid in the investigation of anemia CBC FBC parameters blood smear exam Reticulocyte count Iron studies serum iron TIBC serum ferritin Red cell destruction tests eg bilirubin haemoglobin electrophoresis Vitamin B12 and folate levels Direct antiglobulin test Bone marrow examination and other tests as indicated Reticulocyte Counts Measures the rate of RBC production by the bone marrow Retics appear as polychromasia on a Wright s stained blood smear a retic count must be done for number Automated or manual using a supravital stain Stain precipitates RNA into filaments or granules New methylene blue is commonly used Supravital Stain NRBC Polychromasia Wright s stained smear Reticulocytes Supravital stained smear Reticulocyte Counts Two dots or more is a retic Count 500 red cells using 100x oil immersion separating mature red cells and retics 1000 total red cells are counted of retics 500 RBCs must agree 2 retics or another slide is counted Reported in relative number and absolute Reticulocytes Supravital stain Artifact Supravital stain Reticulocyte Counts Calculations and reporting Retics are expressed in relative number percent to nearest tenth The relative retic count is the number of retics in 1000 RBC s Retics are also expressed in absolute number thousands cmm to nearest thousand The absolute retic count is the retic times the RBC count cmm Reticulocyte Counts Absolute is more reliable than Sources of error Reference range Adult 0 5 2 0 25 100 000 cmm Absolute Newborn 2 0 6 0 Significance absolute Retic count Reticulocytosis Increased RBC production Will observe increased amount of polychromatophilic red cells on Wright s stained blood smear absolute Retic count Reticulocytopenia Decreased RBC production For each condition listed what is the expected retic response by the bone marrow Lack of a component essential to produce HGB Normal low absolute retic Reticulocytopenia Bone marrow injury Normal low absolute retic 3 5 days after acute haemorrhage due to EPO High absolute retic Reticulocytosis Reduced RBC lifespan caused by destruction High absolute retic typical of haemolytic anemias Erythropoiesis RBC Survival Erythropoiesis requires Intact marrow function and sufficient erythropoietin Nutrients for Hgb synthesis and cell division Normal RBC survival depends upon maintaining RBC membrane shape and haemoglobin function Under normal conditions constant red cell replacement loss 1 Anemia results when the rate of RBC production does not keep up with red cell loss The Retic count determines the status of bone marrow production of red cells Definition of Anemia Decrease in the RBC count HGB and or HCT values as compared to normal reference range for age and sex True anemia decreased RBC mass and normal plasma volume Pseudo or dilutional anemia normal RBC mass and increased plasma volume Pregnancy volume overload congestive heart failure Functionally defined as tissue hypoxia Commonly encountered condition with many causes sign of deficiency or disease Definition of Anemia Haematologic Response to Anemia Tissue hypoxia causes increased renal release of erythropoietin to accelerate bone marrow erythropoiesis The normal bone marrow can increase its activity 7 8x normal Marrow becomes hypercellular M E ratio falls Nucleated RBCs may be released along with reticulocytes NRBC tends to correlate with the severity of anemia If demand exceeds maximal marrow activity production can occur in extramedullary sites Signs of Accelerated Bone Marrow Erythropoiesis Nucleated Red Cell Polychromasia Wright s stained blood smear Physiologic Response to Anemia Ability to adapt to anemia depends on Symptoms of hypoxia Age and underlying disease Cardio pulmonary function Rate anemia develops Fatigue dizziness headaches Dyspnea poor exercise tolerance cardiac stress General physical findings Pallor rapid pulse Pallor Physical Signs Methods of Anemia Classification Morphologic Anemia is divided into three groups mainly on the basis of the MCV RBC indices Etiologic Anemia is divided using two main causes mechanisms Decreased delivery of red cells to the blood retic count is inappropriately low The bone marrow fails to respond appropriately due to disease or lack of essential supplies Increased loss of red cells from the blood retic count is typically high Anemia results when red cell loss exceeds the bone marrow s capacity to increase its activity 3 Morphologic Categories of Anemia 2 1 1 Microcytic hypochromic 2 Macrocytic normochromic 3 Normocytic normochromic 3 Classification of Anemia Anemia Diagnosis Cause The cause of anemia is identified with laboratory tests as well as consideration of patient history and physical signs clinical symptoms Patient evaluation Age sex ethnic background family history Nutritional and hydration status pregnancy Exposure to toxins or drugs Disease history eg inflammation Treatment Patient symptoms and anemia severity determine the need for a blood transfusion Lab Investigation of Anemia Begins with CBC FBC parameters and blood smear evaluation Detects mild 10 g dl Hgb to Severe anemia 8 g dl Hgb RBC indices MCV are used to classify anemia RBC morphology abnormalities can be diagnostic or suggest a cause that guides further